Heating element



June 10, 1941. c. F. GRAM HEATING ELEMENT Filed Dec. 2, 1936 Patented June 10, 1941 UNITED STATES PATENT OFFICE HEATING ELEMENT Carl F. Gram. Elisabethton, Tenn., assignor to North American Rayon Corporation, New York, N. Y., a corporation of Delaware Application December 2, 1936, Serial No. 113,876

4Claims.

7 their passage thereover.

It has been known in the art, in so-called continuous process machines to heat yarn conveying rollers by heating elements mounted within the roller whereby the yarn receives the drying heat by conduction. This method results in considerable loss of heat with a resulting higher cost of production.

Another method of drying yarn has been to heat the rollers by gas-bumers resembling the Bunsen type. Such burners give of! a narrow fanshaped flame which is directed against the surface of the roller at a point which the yarn being conveyed is not in contact with at the time.

When drying yarn in continuous lengths with an open flame the thread is conveyed in an approximately helical path over a pair of spaced rotating rollers positioned at an angle to one another. The

burner is situated below the top roller and fixed or mounted on a stationary support between the two rollers. The flame must be so adjusted that perfect combustion is obtained to avoid depositing soot or other contaminations on the roller which would result in damage to the yarn; This method of heating the surface of the roller has usually' been considered the proper and best method for drying yarn in continuous lengths.

Although the aforementioned method has been combustion is also another great disadvantage.

It is'therefore one object of the present invention to devise a heating element for yarn which may be readily and positively controlled.

Another object of the present invention is to devise a heating element which concentrates the heat rays mainly through reflection whereby a minimum amount of heat energy is lost.

A further object of the present invention is to devise a novel heating element for drying yarn or thread which will not impair the quality thereof.

Still another object of the present invention is to devise a heating unit which is adapted to direct back to the surface to be heated all radiated rays which were not initially directed to that surface.

These and other objects of the present invention will in part become obvious and in part be pointed out hereinafter.

To the attainment of the aforesaid objects and ends, my invention consists in the novel features of construction and in the combination, construction and in the combination, connection and arrangement of parts, hereinafter more fully described and illustrated in the accompanying drawing and then pointed out in the appended claims.

In the drawing:

Fig. l is a side elevation of a pair of spaced thread conveying rollers with my invention illustrated in operative position thereto.

Fig. 2 is an end elevation of the parts shown in Fig. 1.

Fig. 3 is enlarged detail view of one end of one of the rollers and my heating element in operative position thereto.

Fig. 4 is an enlarged end elevation of the parts shown in Fig. 3.

Fig. 5 is an enlarged section taken on the line A-A of Fig. 3.

In the drawing in which like numerals of reference indicate like parts in all of the figures, I and 2 indicate the spaced rollers over which the thread 3 is conveyed in an approximately helical path from one end of the said rollers to the other end thereof.

The rollers I and 2 are mounted on a frame 4 and are driven by any suitable means (not shown). These rollers I and 2 are positioned so that their axes are at a slight angle, one to the other, whereby the thread or yarn, during the rotation of the rollers, is passed in a well known maner in spirals thereover.

The wet-treated threads are passed to the rollers I and 2 for the purpose of being dried thereon.

The novelty of the invention lies in the concentration of heat rays on the surface of a roller or rollers through radiation and reflection, whereby the heat applied may be controlled and directed with a minimum loss of heat energy.

The heating element I may and does consist of any well known resistance element such as a wire. coiled or straight, a carborundum rod. etc., which is heated to the desired temperature by electricity.

The radiant element 5 is partly surrounded by a polished reflector 6 which catches all heat rays not directed to the roller and concentrates them by reflection on the surface of the roller I. The roller 2 in this embodiment serves also as guide means for the heated roller I.

The curve of the reflector 8 may be a conic section or a combination of conic sections. It may be so designed that all the heat rays are concentrated in a very confined area, thereby obtaining very high temperature on the surface to which they may be applied, or the major portion of the rays may be concentrated in a confined area on the roller and the remainder of the heat rays distributed with less intensity on one or both sides of the center to create a preheating zone, or an after-heating zone, or both.

The heating element 5 has the usual terminal contacts I and 8 to which the current carrying wires 9 and ID are attached.

The wires 9 and I pass through the hollow support II on which the heating unit is mounted To regulate the temperature of the heat rays applied a rheostat control l2 may be used in conjunction with the heating unit, or preferably a transformer to regulate the voltage applied, which prevents loss of energy occurring in a rheostat.

By means of the novel device heat transfer from the source to the point of utilization can be carried out with practically no heat loss, since all heat issuing from the source is fully and uniformly applied to the rollers.

The heat which is carried away from the source by convection is brought into close contact with the curved surface due to the proximity of the said source to the roller.

The minor portion of the heat rays are transferred to the curved surface by radiation. The major portion of the heat rays which are ordinarily lost are caught by the reflector' and redirected back to the surface of the roller. The reflected rays are directed and controlled according to the calculated curve of the reflector and the position of the heating element with respect thereto. It is clearly apparent that this novel heating unit reduces to a minimum the usual loss of heat encountered in the drying of continuous thread lengths.

It is of course understood that the reflector 6 should have a highly polished reflecting surface and that, further, the reflector may and should be insulated.

The reflector may be made of double glass walls, evacuated between, and having the surface facing the roller coated with a silver reflecting surface.

It is preferable to have the reflector start to curve inwardly as it nears the roller or curved surface so that no direct heat rays escape through the space between roller and reflector edge. For similar considerations, it is desirable to place the heating element at one focus of an elliptical reflector and the heated surface at the other focus. This arrangement is indicated in Fig. 4

Further means may be supplied to change the relative position of the heating element and the reflector 6 whereby different concentrations of the heat waves may be regulated. In the drawing screws l3 are shown for changing the position of the heating element relative to the reflector. As shown in Fig. 5 the heating element 5 is held in alignment by brackets l4 provided on both sides of the reflector 6, and is freely slidable along the surfaces I5 so that by adjusting the screws l3 it may be raised and lowered. However, it might be desirable to change the position of the reflector, or both, and applicant therefore does not wish to be limited solely to the adjusting means shown.

From the foregoing description, taken in connection with accompanying drawing it is thought the complete construction, operation and advantages of my invention will be clear to those skilled in the art to which it pertains.

It is to be understood that the form of my invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. Apparatus for drying a continuous length of yarn, thread, or the like comprising, in combination, a rotatable cylinder, a heating element adjacent the periphery of said cylinder and adapted for transmitting heat thereto through radiation, a reflector curved in the form of a conic section partly surrounding said heating element and arranged to reflect back to the periphery of said cylinder all heat rays which had not been directed thereagainst, and means for guiding the yarn, thread, or the like over the rotatable cylinder.

2. Apparatus for drying a continuous length of yarn, thread, or the like comprising, in combination, a rotatable cylinder, a heating element adjacent the periphery of said cylinder for heating said periphery through radiation, a reflector partly surrounding said heating element, said reflector being curved in a conic section and having its ends adjacent said periphery and bending inwardly whereby no direct heat rays escape between said periphery and said reflector ends, and means for guiding the yarn, thread, or the like over the rotatable cylinder.

3. Apparatus for drying a continuous length of yarn, thread, or the like comprising, in combination, a rotatable cylinder, a radiant heating element fixed adjacent said cylinder, an elliptical reflector partly surrounding said heating element, said heating element being positioned within the reflector at one focus thereof, and means for guiding the yarn, thread, or the like over the rotatable cylinder, said cylinder and reflector between them being arranged completely to surround the heating element except for the clearance necessary to permit rotation of the cylinder. 

